Fluorescent Aryl Research Articles

Organosilicon Fluorescent Materials.

In the past few decades, organosilicon fluorescent materials have attracted great attention in the field of fluorescent materials not only due to their abundant and flexible structures, but also because of their intriguing fluorescence properties, distinct from silicon-free fluorescent materials. Considering their unique properties, they have found broad application prospects in the fields of chemosensor, bioimaging, light-emitting diodes, etc. However, a comprehensive review focusing on this field, from the perspective of their catalogs and applications, is still absent. In this review, organosilicon fluorescent materials are classified into two main types, organosilicon small molecules and polymers. The former includes fluorescent aryl silanes and siloxanes, and the latter are mainly fluorescent polysiloxanes. Their synthesis and applications are summarized. In particular, the function of silicon atoms in fluorescent materials is introduced. Finally, the development trend of organosilicon fluorescent materials is prospected.

Selective fluorescence labeling of myristicin using Mizoroki-Heck coupling reaction. Application to nutmeg powder, oil, and human plasma samples

Myristicin [5-allyl-1‑methoxy-2,3-(methylenedioxy)benzene] is the major constituent of the seasoning nutmeg oil and powder. Sometimes myristicin is abused via its ingestion at high doses to cause hallucination. In these high doses, myristicin could cause severe adverse health effects, including convulsion, delirium, and palpitation. Hence there is a strong need for a sensitive method for its analysis, such as fluorescence determination. Myristicin has a very weak fluorescence and also lacks derivatizable groups like the carboxylic, hydroxyl, or amino group in its structure, which makes its fluorescence derivatization challenging. In this research, we developed a fluorescence labeling method for myristicin based on the Mizoroki-Heck coupling reaction of its terminal alkene with a fluorescent aryl iodide derivative, 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIB-I). Then, we developed an HPLC fluorescence detection method for the determination of myristicin utilizing this labeling reaction. The developed method showed a good linear response for myristicin (r = 0.995) in the range of 0.01–10 µmol/L with excellent sensitivity down to the detection limit of 2.9 nmol/L (9.6 fmol/injection). Finally, the developed method could be successfully applied to determine myristicin content in nutmeg powder, oil samples, and human plasma with simple extraction methods and good recoveries ranging from 89.3 to 106%.

Exploring the Effect of Aliphatic Substituents on Aryl Cyano Amides on Enhancement of Fluorescence upon Binding to Amyloid-β Aggregates.

The self-assembly of amyloid-β (Aβ) peptides into amyloid aggregates is a pathological hallmark of Alzheimer's Disease. We previously reported a fluorescent Aryl Cyano Amide (ARCAM) probe that exhibits an increase in fluorescence emission upon binding to Aβ aggregates in solution and in neuronal tissue. Here, we investigate the effect of introducing small aliphatic substituents on the spectroscopic properties of ARCAM both free in solution and when bound to aggregated Aβ. We found that introducing substituents designed to hinder the rotation of bonds between the electron donor and acceptor on these fluorophores can affect the overall brightness of fluorescence emission of the probes in amyloid-free solutions, but the relative fluorescence enhancement of these probes in amyloid-containing solutions is dependent on the location of the substituents on the ARCAM scaffold. We also observed the capability to tune the excitation or emission wavelength of these probes by introducing electron-donating or -withdrawing substituents that putatively affect either the energy required for photoexcitation or the stability of the photoexcited state. These studies reveal new design principles for developing ARCAM-based fluorescent Aβ-binding probes with an enhanced fluorescence signal compared to background and tunable spectroscopic properties, which may lead to improved chemical tools for aiding in the diagnosis of amyloid-associated neurodegenerative diseases.

The Utility of Sonogashira Coupling Reaction for the Derivatization of Aryl Halides with Fluorescent Alkyne.

Aryl halides are a very important category of compounds that include many vital drugs and key industrial additives, such as clofibrate and bromobenzene, respectively. Due to their importance, our research group previously developed a novel fluorescence labeling approach for their analysis using a fluorescent aryl boronic acid as a reagent, based on the Suzuki coupling reaction. This coupling reaction was successfully applied for the determination of aryl halides in biological fluids; however, there was a limitation of low reactivity towards ortho-substituted aryl halides. In the present study, a novel fluorescence derivatization approach for aryl halides was developed using, 2-(4-ethynylphenyl)-4,5-diphenyl-1H-imidazole (DIB-ET) as a fluorescent alkyne reagent, based on the Sonogashira coupling reaction. DIB-ET reacted with aryl bromides in the presence of palladium and copper as catalysts, yielding fluorescent derivatives that could be subsequently determined by an HPLC system with fluorescence detection. The detection limits (S/N = 3) for aryl bromides were in the range of 14 - 23 nM, which is 3.5 - 18-times more sensitive than our previously developed approach, Suzuki coupling derivatization. Moreover, in contrast to the previous technique, the reactivity of DIB-ET to ortho-substituted aryl bromides was almost equivalent to that of the para-substituted aryl bromides. Hence, by using this newly developed approach we could label the aryl halides with more sensitivity and reactivity. Finally, the proposed method was successfully applied for the selective determination of aryl bromides in human serum with good recovery (84.6 - 107%), which proves the ability of the developed method to determine occupational exposure to aryl halides.

Nanomolar level detection of explosive and pollutant TNP by fluorescent aryl naphthalene sulfones: DFT study, in vitro detection and portable prototype fabrication

Luminescent Aryl Naphthalene Sulfones have been prepared via Garratt-Braverman cyclization of γ-substituted bis-propargyl sulfones for explosive and pollutant 2,4,6-Tri nitrophenol (TNP) recognition in aqueous medium by fluorescence quenching. The quenching can be explained through AIE-ACQ-RET-ICT based mechanisms. In vitro detection of TNP has been performed inside pollen cells. In real time stepping, paper strip and pocket solution kit has been fabricated for on spot detection of TNP. Moreover as an analytical application TNP has been detected from several surface water specimens collected throughout West Bengal, India. The limit of detection has been found as low as 10nM together with quenching constant as 6.8×105M−1, which is even superior to the recently published sensor materials.

Fluorescent Carbon Nanotube Defects Manifest Substantial Vibrational Reorganization

Fluorescent defects have opened up exciting new opportunities to chemically tailor semiconducting carbon nanotubes for imaging, sensing, and photonics needs such as lasing, single photon emission, and photon upconversion. However, experimental measurements on the trap depths of these defects show a puzzling energy mismatch between the optical gap (difference in emission energies between the native exciton and defect trap states) and the thermal detrapping energy determined by application of the van ’t Hoff equation. To resolve this fundamentally important problem, here we synthetically incorporated a series of fluorescent aryl defects into semiconducting single-walled carbon nanotubes and experimentally determined their energy levels by temperature-dependent and chemically correlated evolution of exciton population and photoluminescence. We found that depending on the chemical nature and density of defects, the exciton detrapping energy is 14–77% smaller than the optical gap determined from photoluminesce...

Fluorescent aryl naphthalene dicarboximides with large Stokes shifts and strong solvatochromism controlled by dynamics and molecular geometry

A series of highly fluorescent 4-aryl substituted naphthalene dicarboximides were efficiently prepared via metal organic C–C-coupling reactions.

Ortho-Substituted fluorescent aryl monoboronic acid displays physiological binding of d-glucose

An ortho-fluorinated phenylboronic acid incorporated into the BODIPY-fluorophore, sensor 1, exhibits a significant response in emission intensity upon binding of d-glucose and d-fructose. This sensor displays a desired binding strength toward d-glucose at the physiological level, that is Kd values between 10 and 20mM. This binding strength of sensor 1 has been shown to be independent of the employed buffer, that is, saline buffer, 50mM phosphate buffer, and 50mM phosphate buffer in 52.3 w/w% MeOH. The d-glucose binding strength and the fluorescence response of a BODIPY-based ortho-methylated phenylboronic acid, sensor 2, show a significantly decreased d-fructose binding affinity. This sensor also exhibits buffer-dependent binding strength and fluorescence response upon binding of d-glucose and d-fructose.

Air‐Stable, Highly Fluorescent Primary Phosphanes

Air‐Stable, Highly Fluorescent Primary Phosphanes

Charge‐Carrier Balance and Color Purity in Polyfluorene Polymer Blends for Blue Light‐Emitting Diodes

AbstractA study of an efficient blue light‐emitting diode based on a fluorescent aryl polyfluorene (aryl‐F8) homopolymer in an inverted device architecture is presented, with ZnO and MoO3 as electron‐ and hole‐injecting electrodes, respectively. Charge‐carrier balance and color purity in these structures are achieved by incorporating poly(9,9‐dioctylfluorene‐co‐N‐(4‐butylphenyl)‐diphenylamine (TFB) into aryl‐F8. TFB is known to be a hole‐transporting material but it is found to act as a hole trap on mixing with aryl‐F8. Luminance efficiency of ≈6 cd A−1 and external quantum efficiency (EQE) of 3.1% are obtained by adding a small amount (0.5% by weight) of TFB into aryl‐F8. Study of charge injection and transport in the single‐carrier devices shows that the addition of a small fraction of hole traps is necessary for charge‐carrier balance. Optical studies using UV–vis and fluorescence spectroscopic measurements, photoluminescence quantum yield, and fluorescence decay time measurements indicate that TFB does not affect the optical properties of the aryl‐F8, which is the emitting material in these devices. Luminance efficiency of up to ≈11 cd A−1 and EQE values of 5.7% are achieved in these structures with the aid of improved out‐coupling using index‐matched hemispheres.

Labeling of alprenolol with fluorescent aryl iodide as a reagent based on Mizoroki–Heck coupling reaction

A novel fluorescent labeling method for alprenolol was developed based on Mizoroki–Heck coupling reaction. We designed and synthesized fluorescent aryl iodide, 4-(4,5-diphenyl-1 H-imidazol-2-yl)iodobenzene (DIBI) as a labeling reagent. DIBI has a lophine skeleton carrying an iodide atom acting as fluorophore and reactive center, respectively. In order to evaluate the usefulness of DIBI, a high-performance liquid chromatography (HPLC) with fluorescence detection method was developed for the determination of alprenolol as a model compound of terminal double bond. The fluorescent labeling of alprenolol with DIBI was achieved in the presence of palladium acetate as a catalyst, and the labeled alprenolol was detected fluorometrically. In addition, it was found that the fluorescence of DIBI derivative increased and red shifted when compared with that of DIBI. Furthermore, the proposed method could be applied to determine the alprenolol concentration in rat plasma after administration of alprenolol without interferences from biological components. The detection limit (S/N = 3) for alprenolol in rat plasma was 0.74 ng/mL (30 fmol on column).

New fluorescent aryl- or ethynylaryl-boron-substituted indacenes as promising dyes

A generic design principle based on the use of organometallic (Li or Mg) reagents for the substitution of the fluoro ligands in difluoroboradiazaindacene is described. A library of compounds bearing various substituents (butyl, phenyl, naphthyl, pyrenyl, ethynylnaphthyl, ethynylfluorenyl, ethynylcarbazoyl, ethynylperylenyl, ethynylthiophenyl and ethynylterpyridinyl) has been prepared and characterized. Electrochemical and photochemical measurements show that these novel dyes remain redox-active and strongly luminescent. They offer an interesting perspective for applications in labelling and electroluminescence.

Fluorescence microscopy of stimulated Zn(II) release from organotypic cultures of mammalian hippocampus using a carbonic anhydrase-based biosensor system

We demonstrate here that electrical stimulation of organotypic cultures of rat hippocampus results in the prompt release of significant amounts of Zn(II) by a fluorescence microscopic method. The fluorescence imaging of free Zn(II) is achieved using a highly selective biosensing indicator system consisting of human apo-carbonic anhydrase II (apoCAII) and a fluorescent aryl sulfonamide inhibitor of the enzyme, ABD-N. The apoenzyme and ABD-N in the absence of Zn(II) exhibit weak, reddish fluorescence typical of the ABD-N alone; when Zn(II) is added it binds to the apoenzyme ( K D=4 pM), which strongly promotes binding of ABD-N to the holoenzyme ( K D=0.9 μM). Binding of ABD-N to the holoenzyme results in a 9-fold increase in apparent quantum yield, significant blue shifts in excitation and emission, an increase in average fluorescence lifetime, a 4-fold increase in the ratio of intensities at 560 and 680 nm, and a large increase in anisotropy. Prior to stimulation, cultures immersed in phosphate-buffered saline with glucose and apoCAII with ABD-N emitted negligible fluorescence, but within 20 s after electrical stimulation a diffuse cloud of greenish fluorescence emerged and subsequently covered most of the culture, indicating release of zinc into the extracellular medium.

Photochemical Coupling of Aryl Azides to Poly(ether urethane) Surfaces: Studies with a Fluorescent Model Compound

A fluorescent aryl azide [N-methyl-N-(2-hydroxyethyl)-5-(dimethylamino)naphthalene-1-sulfonamide 4-azidobenzoate] (2) was synthesized as a model compound for aryl azides that are used for the photochemical surface modification of poly(ether urethanes) (PEUs). We are using this method of surface modification in our search for artificial surfaces with optimized blood compatibility. As a part of this work, two pivotal questions are now addressed: (i) what is the surface density of coupled molecules that can be reached by this method and (ii) is binding to the surface really covalent? After the photochemical coupling of 2 to a PEU surface, the ester bonds of the coupled molecules were selectively hydrolyzed with 0.1 M NaOMe/MeOH and the concentration of fluorescent molecules in solution determined spectrofluorometrically. Since not all of the fluorescent molecules were removed by this procedure, an additional experiment was performed (in which the polymer was completely dissolved). It was found that 25 nmol/cm2 had coupled to the outermost polymer layers and 7.7 nmol/cm2 to polymer layers more within the material (unreachable for the NaOMe/MeOH reagent). In another experiment a modified PEU sheet was dissolved in THF, after which MeOH was added to precipitate it again. From the fact that no fluorescence was detected in solution it could be concluded that all of the fluorescent molecules were indeed covalently coupled to the polymer surface.